Temperature control system



Nov. 21, 1939. w L. MCGRATH 2,181,061

TEMPERATURE CONTROL SYSTEM Filed Sept. 5, 1935 awe/whom Patented Nov.21, 1939 UNITED STATES PATENT OFFICE TEMPERATURE CONTROL SYSTEM DelawareApplication September 5, 1935, Serial No. 39,264

6 Claims.

This invention relates to temperature control systems of the typedisclosed in United States Patent No. 2,065,835 granted to Daniel G.Taylor on December 29, 1936.

The system disclosed in the above referred to Taylor applicationcomprises an outdoor controller responsive to outdoor atmosphericconditions, including temperature, wind and solar radiation forcontrolling the temperature within the building. Heating means areprovided in the building for supplying heat to the building, and heatingmeans are also provided in the outdoor controller for supplying heat tothe outdoor controller. The two heating means are proportioned accordingto the heat losses from the building and from the outdoor controller. Athermostatic device is provided in the outdoor controller for respondingto the temperature within the outdoor controller, and when thisthermostatic device calls for heat both of the heating means areenergized simultaneously to deliver heat to the building and to theoutdoor controller. Due to the proportional relationship of the heatingmeans with the heat losses of the building and theoutdoor controller, adefinite temperature relation is maintained within the building and theoutdoor controller so that by responding to the temperature of theoutdoor controller, the thermostaticdevice maintains a substantiallyconstant or normal temperature 30 within the building.

Such a system may be readily adapted to a building heating system havinga valve for admitting heating fluid to the radiation surfaces within thebuilding. The heating fluid may be steam which may be supplied from aconstantly energized boiler or a central power plant. The valve may beopened simultaneously with the energization of the outdoor controllerheater upon a call for heat by the outdoor controller. However, it hasbeen found that the rate of flow of steam through such a valve is notconstant but varies. These variations in rate of flow may be attributedto changes in steam supply pressures, to changes in rate of condensationin the heating system which results in varying outlet pressures at thevalve, 'to the condition of the heating system just after the valve isopened depending upon whether the system is full of steam or whether itcontains a vacuum caused by rapid condensation of the steam supplied tothe frequency of operation of the valve, to the length of time which thevalve is opened and to other causes. Therefore, a valve which controlsthe supply of steam to a heating system does not necessarily admit twiceas much steam when the valve is opened, say twenty minutes, than whenthe valve is opened only ten minutes.

The successful operation of such a heating system depends upon theability to maintain the ratio of the heat supplied to the building andto the outdoor controller constant regardless of the conditions whichtend to vary the rate of the flow of heating fluid to the radiationsurfaces within the building.

It is therefore an object of this invention to provide means wherebyheat may be supplied to a building or space at a constant rate upon'acall for heat.

It is another object of this invention to provide a heating system for abuilding or space wherein the heating system is operated in accordancewith outdoor atmospheric conditions and where-- in the rate of heatsupply to the building or space is maintained constant.

Still another object is to provide a control system for a buildingheating system having a control valve, wherein the control valve isopened in response to a call for heat and wherein the amount of valveopening may be varied to maintain a constant rate of flow of heatingfluid to the heat exchangers within the building.

' A further object is to provide a control system for a building heatingsystem wherein the control system comprises an outdoor controllersubject to the same atmospheric conditions as the building includingtemperature, wind and solar radiation, the controller including a heat-'ing means and a thermostatic means which operates the heating means andthe building heating system along with means whereby the rate at whichheat is supplied to the building may be maintained constant during theperiods when there is a call for heat.

Other objects and advantages will become apparent to those skilled inthe art upon reference to the accompanying specification, claims anddrawing, in which drawing is diagrammatically illustrated the preferredform of my invention.

My control system is shown as applied to a building having an outsidewall 10 and a plurality of spaces or rooms to be heated, II and 12.Located in the spaces or rooms are radiators, or heat exchangers l3which receive a supply of heating fluid, such as steam, from risers l4,under the control of manually operated valves IS. The risers I4 connectinto a header 16. A pipe I! emanating from some source of heating fluidsuch as a constantly energized boiler, or a central heating plant,supplies heating fluid to a .on a shaft 24.

and 371'.

pipe l9 under the control of a valve l8, the pipe l9 being connected tothe header iii. The arrangement is such that when the valve I8 is openheating fluid is supplied through the pipe l9, the header "5 and therisers M to the radiators B3 to heat the rooms II and i2. When the valveI8 is closed, the further supply of heating fluid to the radiators i3 isprevented.

The valve I8 is operated by a valve stem which is connected to one endof a pitman 29. The other end of the pitman 2i is'connected to a crankpin 22 carried by a crank disc 23, mounted Shaft 24; is operated by aproportioning motor and may take the form of the motor shown anddescribed in application Serial No. 673,236, filed by Lewis L.Cunningham on May 27, 1933.

For purposes of illustration in this application, I have shown theproportioning motor to comprise a gear 25 mounted on the shaft 25 whichis driven through a reduction gear train 26 by motor rotors 2'5 and 28.The motor rotors 2i and 28 are operated by field windings 29 and 35,respectively, the arrangement being such that when the field winding 25is energized the valve :15 is moved to a closed position, and When thefield Winding 30 is energized the valve H8 is moved to an open position.The shaft 25 may carry also a bevelled gear 3i meshing with anotherbevelled gear 52 which carries an abutment member 33. The abutmentmember 53 is provided with a slider 55 which is adapted to slide acrossa balancing potentiometer coil 35. The abutment member 53 also carriesspaced fingers 55 The finger is adapted at one extrerne position of theabutment member 55 to break contact between contacts and Likewise, thefinger 37 is adapted to break contact between contacts 55 and M at theother extreme position of the abutment member The contacts 55, 15 andli, therefore, form limit switches.

Located outside of the building so as to be subject to the sameatmospheric conditions as the building, including temperature, wind andsolar radiation, is an outdoor controller This outdoor controller l5comprises a metallic block Q5 which is hollowed out to receive acontainer t'l Located in the container M is a bimetallic element 65mounted on a post 59. The container ii is closed by a cover 55 so thatthe bimetallic element Will not be directly affected by the outdooratmospheric conditions but will respond directly to the temperature ofthe block 15. The bimetallic element 55 carries nontaots 5i and 52 whichare adapted to sequentially engage adjustable contacts 55 and 55 upon adecrease in block temperature. The block 55 is cooled by outdooratmospheric conditions and heated by means of a heater 55 located inclose proximity with the block 35. The elements comprising the outdoorcontroller 55 may be enclosed within a casing 55 to preventdeterioration of the same by the weather conditions.

A relay coil 571 is adapted to operate switch arms 58, 59 and 55 withrespect to contacts iii, 52, 55 and 541. Upon energization of the relaycoil 57, the switch arms 58, 55 and 55 are moved into engagement withthe contacts 55, 52 and 55, respectively, and upon deenergization of therelay coil 5?, the switch arms 58, 59 and Gil are moved out ofengagement with the contacts. (M, 52 and 55, and the switch arm Mi ismoved into engagement with the contact fi l.

- Line wires leading from some Source of power,

not shown, are designated at 65 and 66. A primary 61 of a step-downtransformer 68, having a secondary 69 is connected across the line wires65 and 66. One end of the secondary 69 is connected by a wire 10 to theadjustable contact 53 of the outdoor controller 45. The other adjustablecontact 54 is connected by wires II and 12 to one end of the relay coil51. The other end of the relay coil 51 is connected by a wire 13 to theother end of the secondary B9. The bimetallic element 48 of the outdoorcontroller is connected by a wire 14 to the contact BI, and the switcharm 58 which cooperates with the contact M is connected by a wire l5 tothe junction of wires H and 712.

A primary E6 of a step-down transformer 11, having a secondary 115, isalso connected across the line wires 55 and 65. One end of the secondaryit is connected by a wire '89 to the contact 62. Switch arm 59, whichcooperates with the contact 62, is connected by a wire 80, a manuallyoperated variable resistance M, an ammeter 82, and a wire 83 to one endof the heater 55. The other end of the heater 55 is connected by a wire85 to the other end of the secondary it. The variable resistance ti andthe ammeter 52 provide a means for adjusting and visually indicating theamount of heat supplied to the block 55 by the heater 55.

Upon a decrease in temperature of the block 55, the contact 59 is movedinto engagement with the contact 55, and upon a further decrease inblock temperature, the contact 52 is moved into engagement with thecontact 5 5. This causes completion of a circuit from the secondary 65,through wire 05, contacts 55, 5t, 52 and 5 wires M and E2, relay coil5ll and wire it back to the secondary 55. Completion of this circuitcauses energization of the relay coil 5i to move the switch arms 55, 5t]and Gil into engagement with the contacts til, 52 and 55. Movement ofthe switch arm 58 into engagement with the contact 5i completes amaintaining circuit from the secondary 65, through wires ill, contacts55 and 5t, bimetallic element 58, wire ll l, contact ti, switch arm 55,wires l5 and E2, relay coil 511 and wire 75 back to the secondary 55.This maintaining circuit maintains the relay coil 5i energized untilcontact between the contacts'5l and 53 is broken.

Movement of the switch arm 59 into engagement with the contact 52completes a circuit from the secondary it through wire 59, contact 52,switch arm 55, wire till, variable resistance til, ammeter 52, wire 55,heater'55 and wire 84, back to the secondary :18. This causesenergization of the heater 55 to increase the temperature of the block55. When the temperature of the block 55 has increased to apredetermined value so as to break contact between the contacts 5i andthe relay coil 5'1! is deenergized and the switch arms 55, 55 and 55 aremoved out of engagement with the contacts 58, 52 and B3, and the switcharm 55 is moved into engagement with the contact 56. This causesdeenergization of the heater 55 to prevent the further supply of heat tothe outdoor controller until such time as the temperature of the block35 shall so decrease to move the contacts 5i and 52 into engagement withthe contacts 53' and 55.

Located in the pipe l9 which supplies heating fiuid, such as steam, tothe header i6, is an orifice plate 55. The pipe 55 connects into thepipe B9 on the high pressure side of the orifice plate and leads to theupper end of a pressure chamber 81. A pipe 88 extends from the pipe I9on the low pressure side of the orifice plate 85 to the lower portion ofthe pressure chamber 81. Located in the pressure chamber 81 is aninverted bell 89 which is adapted to float upon and be sealed by a poolof mercury designated at 90. The float 89 and the mercury seal,therefore,

divide pressure chamber 81 into the high pres-' sure chamber locatedabove the bell 89, and a low pressure chamber located within the bell89. The bell 89 operates a rod or arm 9I which carries a slider 92 whichis adapted to slide across a potentiometer coil 93. By reason of theorifice plate 85, the pressure chamber 81 and the connections betweenthe same, the slider 92 is moved upwardly or downwardly-in response tochanges in the rate of flow of the heating fluid through the pipe I9.The arrangement is such that upon an increase in the rate of flow withinthe pipe I9, the inverted bell 89, and consequently the slider 92, aremoved downwardly, and upon a decrease in the rate of flow through thepipe I9, the bell 89, and consequently the slider 92 are moved upwardly.The potentiometer coil may be made adjustable longitudinally so that itmay be moved with respect to the slider 92 whereby the controllingaction of the flow controller may be adjusted.

Oppositely acting coils are designated at 95 and 96, and these coilscontrol the operation of an armature or core 91 which is connected bymeans of a spring 98 to a pivoted switch arm 99. The switch arm 99cooperates with the spaced contacts I and I DI When the coil 95 is ener-'zed more than the coil 96, the switch arm 99 is moved into engagementwith the contact I00, and when the coil 96 is energized more than thecoil 95, the switch arm 99 is moved into engagement with the contactIOI. When the coils 95 and 96 are equally energized, the switch arm 99assumes a position midway between the contacts I00 and IOI, as shown inthe drawing.

Also connected across the line wires 65 and 66 is a primary I03 of astep-down transformer I04, having a secondary I05. One end of thesecondary I05 is connected by wires I06 and I01 to one end of the coil95, and likewise, the other end of the secondary I05 is connected bywires I08 and I09 to one end of the coil 96. v The other ends of thecoils 95 and 96 are connected together, The junction of wire I01 and thecoil 95 is connected by a protective resistance III) and wires I II andH2 to the left-hand end of the balancing potentiometer coil 35 and tothe upper end of the potentiometer coil 93. In a like manner, thejunction of wire I09. and the coil 96 is connected by a protectiveresistance I I3 and wires H4, H5, H6 and H1 to the right-hand 4 end ofthe balancing potentiometer coil 35 and the lower end of thepotentiometer coil 93. The

junction of the coils 95 and 96 is connected by wires I I8, H9 and I tothe slider 34 which cooperates with the balancing potentiometer coil 35and the switch arm 60. The contact 64 is connected by a wire I2I to thejunction of the wires tiometer coil 93 are connected together, and that.

the lower end of the secondary I 05, ,the righthand ends of the coil 96and the balancing potentiometer coil 35, and the lower end of thepotentiometer coil 93 are connected together. Likewise, the junction ofthe coils 95 and 96 and the sliders.34 and 92 are connected together. Itcan therefore be said that the secondary I05, the coils 95 and 96, thebalancing potentiometer coil 35 and the potentiometer coil 93 areconnected in parallel.

The contact I00 associated with the switch arm 99 is connected by a wireI to a small number of turns of the coil 95 and the contact IN isconnected by a wire I26 to a small number of turns of the coil 96. Theswitch arm 99 is connected by a wire I21 to the adjacent ends of thefield windings 29 and 30. The other end of the consequently, the relaycoil 51 is deenergized.'

The valve I 8 is in a closed position preventing the flow of heatingfluid through the pipe I9 and, consequently, the slider 92 is in theextreme upper position. Upon a decrease in block temperature so as tocause energization of the relay coil 51, the switch arms 59 and 60 aremoved into engagement with the contacts 62 and 63. Movement of theswitch arm 59 into engagement with the contact 62 causes heating of theoutdoor controller 45, the movement of the switch arm 60 into engagementwith the contact 63 places the fluid flow regulator in command of theproportioning motor. With the slider 92 in the upper position shown as aresult of no flow of heating fluid through the pipe I9, a circuit iscompleted from the junction of the coils 95 and 96 through wires H8 andI20, switch arm 60, contact 63, wire I22, slider 92, potentiometer coil93, wires H2 and III, and protective resistance IIO to the other end ofthe coil 95. This circuit causes short-circuiting of the coil 95 todecrease the energization thereof, and by reason of the parallelrelationship pointed out above to increase the energization of the coil96. This unequal energization of the coils 95 and 96 causes righthandmovement of the switch arm 99 into engagement with the contact I0 I.This causes completion of a circuit from the secondary I05 through wiresI08 and I09, a small number of turns of the coil 96, wire I26, contactIOI, switch arm 99, wire I21, field winding 30, wire I30, contacts M and40, and wires I3I and I06, back to the secondary I05. Completion of thiscircuit causes energization of the field winding 30 to move the valve I8towards an open position.

Movement of the valve I8 towards an open position causes right-handmovement of the slider 34 with respect to the balancing potentiometercoil 35, and this right-hand movement causes short circuiting orshunting of the coil 96 to de-- crease the energization of the coil 96and increase the energization of coil 95, it being remembered that thecoil 96 was energized more than the coil 95 by reason of the slider 92being located adjacent the upper end of the potentiometer coil 93. Whenthe slider 34 has been moved sufiiciently far to the right with respectto the balancing potentiometer coil 35 so as to rebalance the coils 95and 96, the switch arm 99 is moved out of engamement with the contact IBl to the mid position shown in the drawing. This causes deenergizationof the field winding 39 to prevent further opening movement of the valvel8. Since the slider 92 is located at the extreme upper position withrespect to the potentiometer coil 93, the slider 34 will have to move tothe extreme right-hand position with respect to thebalancingpotentiometer coil 35 in order to rebalance the coils 95 and95. This necessarily causes complete opening of the valve l8.

When the valve I 8 has thus been opened, the rate of flow of fluidthrough the pipe 09 increases, and as this rate of flow of fluid throughthe pipe l9 increases, the slider 92 is moved downwardly with respect tothe potentiometer coil 93. This downward movement of the slider 92causes short circuiting of the coil 98 to decrease the energizationthereof, and increase the energization of the coil 95. This causesmovement of the switch arm 99 into engagement with the contact W9 to complete a circuit from the secondary 095, through wires I 96 and IN, asmall number of turns oi the coil 95, wire I25, contact tilt, switch arm99, wire I21, fleld minding 29, wire lZli, contacts 58 and 39, and wiresE29 and M38 back to the secondary I05. Completion of this circuit causesenergization of the field winding 29 to move the valve 18 towards aclosed position.

Movement of the valve it towards a closed position causes left-handmovement of the slider 34 with respect to the balancing potentiometercoil 35 to shunt or short-circuit the coil 95 to decrease theenergization thereof, and increase the energization of the coil 95, itbeing remembered that the coil 95 was energized more than the coil 96 bythe'downward movement of the slider 92 with respect to its potentiometercoil 99. When the valve l8 has been moved sufiiciently far towards aclosed position so as to rebalance the coils 95 and 96, the switch arm99 is moved out of engagement with the contact N19 to break the circuitthrough the field winding 29 to stop further closing movement of thevalve it. Therefore, whatever position the slider 92 may be caused totake with respect to the potentiometer coil 93, the valve 18 will assumea like position and in this manner the rate of flow of heating fluidthrough the pipe I9 is maintained constant whenever the switch arm 59 ismoved into engagement with the contact 53.

The above circuits for energizing the field windings 29 and 39 include asmall number of turns of the coils 95 and 95 to forcibly hold the switcharm 99 in engagement with either contact 099 or I0 I, whereby relaychatter is entirely prevented.

When the outdoor controller has become satisfied, so as to deenergizethe relay coil 51, the switch arms 59, 59 and 69 are moved out ofengagement with the contacts til, 92 and 93, and the switch arm 69 ismoved into engagement with switch arm 64. Movement of the switch arm 59out of engagement with the contact 52 prevents the further supply ofheat to the block 45 of the slider 34 must move to the extremeright-hand end of the balancing potentiometer coil 35 in order torebalance the coils 95 and 96 and, therefore, the valve i8 is moved to afull closed position to prevent the further supply of heating fluidthrough radiators or heat exchangers I3.

The fluid flow regulator and the variable resistance 88 are so adjustedthat the amount of heat delivered to the building and to the outdoorcontroller 45 is proportional to the heat losses from the building andfrom the outdoor controller 45. By reason of the .fluid flow controllerpositioning the valve [It to maintain a constant flow of heating fluidto the radiators, and by reason of the fact that the amount of heatdelivered to the outdoor controller 45 is maintained constant, the exactamounts of heat delivered to the outdoor controller and to the buildingare accurately determined to maintain the above referred to proportionconstant regardless of whether the valve it is open for a short periodof time or for a long period of time. As pointed out above, due tocondensation rates, a valve opened a given amount for a period of saytwenty minutes, will not necessarily deliver twice as much heating fluidto the radiators as a ten minute opening of the valve. However, byreason of my construction, the rate of flow to the radiators it duringthe periods that the valve is open is maintained constant regardless ofthe length of the period during which the valve i3 is maintained open,or the frequency of its openings, so that the exact and correctproportionate amounts of heat are delivered to the building and to theoutdoor controller to accurately maintain the above referred toproportion, whereby the building temperature is maintained constant.

Although I have disclosed one form of my invention, it is apparent thatother forms thereof may become apparent to those skilled in the art andconsequently this invention is to be limited only by the scope of theappended claims and the prior art.

I claim as my invention:

1. In a heating system for a buildin the combination of valve means forcontrolling the supply of heating fluid to the building, flow responsivemeans for regulating said valve means to maintain the rate of flow ofthe heating fluid substantially constant when the valve means is openedregardless of normal conditions on the outlet side of said valve, anoutdoor controller subject to thesame atmospheric conditions as thebuilding and including heating means and thermostatic means, and meansincluding said thermostatic means operative upon the temperature towhich said thermostatic means is respon- -sive falling below apredetermined value to cause 7 energization of said heating means andcontrol of said valve means by said flow responsive means independentlyof atmospheric conditions and operative upon the temperature to whichsaid thermostatic means is responsive rising above a predetermined valueto cause deenergization of said heating means and movement of said valvemeans to a minimum flow position.

2. In a heating system for a building, the combination of valve meansfor controlling the supply of heating fluid to the building, flowresponsive means for regulating said valve means to maintain the rate offlow of the heating fluid substantially constant when the valve means isopened regardless of normal conditions on the outlet side of said valve,an outdoor controller subject to the same atmospheric conditions as thebuilding and including heating means and thermostatic means, meansincluding said thermostatic means operative upon the temperature towhich said thermostatic means is responsive falling below apredetermined value to place the valve means under the control of theflow responsive means to cause a flow of heating fluid at a uniform rateand operative upon the tem perature to which said thermostatic means isresponsive rising above a predetermined value to cause movement of saidvalve means to a minimum flow position, and means for causingenergization of said heating means simultaneously with the movement ofthe valve means away from its minimum flow position and for causingdeenergization of the heating means upon movement of the valve to itsminimum flow position.

3. In a heating system for a building, the combination of valve meansfor controlling the supply of heating fluid to the building, flowresponsive means for regulating said valve means to maintain the rate offlow of the heating fluid substantially constant when the valve means isopened regardless of normal conditions on the outlet side of said valve,an outdoor controller subject to the same atmospheric conditions as thebuilding and including heating means and thermostatic means, meansincluding said thermostatic means operative'upon the temperature towhich said thermostatic means is responsive falling below apredetermined value to place the .valve means under the control of theflow responsive means to cause a flow of heating fluid at a uniform rateand operative upon the temperature to which said thermostatic means isresponsive rising above a predetermined value to cause movement of saidvalve means to a minimum flow position, and means for causingenergization of said heating means as long as said valve means is out ofits minimum flow position and is under the control of the flowresponsive means, and interrupting energization thereof while the valvemeans is .in its minimum flow position.

4. In a temperature control system for an enclosure, the combination of,valve means for controlling the supply or temperature changing fluid tothe enclosure, electric motor means for positioning the valve means,first current controlling means operated in response to the rate of flowof the temperature changing fluid, means including circuitconnectionsbetween the electric motor means and the first currentcontrolling means for controlling the operation of the electric motormeans and hence the valve means in accordance with the rate of flow ofthe temperature changing fluid to maintain the rate of flow of thetemperature changing fluid substantially constant, and second currentcontrolling means operated in response to changes in temperatureincluded in said circuit connections for interrupting the circuitconnections between the first current controlling means and the electricmotor means to render the first current controlling means inoperative toposition the electric motor means and for operating the electric motormeans to close the valve means.

5. In a temperature control system for an enclosure, the combination of,valve means for controlling the supply of temperature changing fluid tothe enclosure, control means responsive to the rate of flow of thetemperature changing fluid, intermittently operated control meansincluding means responsive to atmospheric condition outside of theenclosure, and means controlled by both control means for regulating thevalve means intermittently and alternately to interrupt substantiallythe supply of temperature changing fluid to the enclosure or to supplytemperature changing fluid to the enclosure at a substantially uniformrate in a manner to cause the period of time during which the supply oftemperature changing fluid is substantially interrupted with respect tothe period of time the temperature changing fluid is supplied at asubstantially constant rate to vary with changes in outside atmosphericconditions to maintain de sired temperature conditions within theenclosure.

6. In a temperature control system for an enclosure, the combination of,valve means for controlling the supply of temperature changing fluid tothe enclosure, flow responsive means for regulating the valve means tomaintain the rate of flow of the temperature changing fluidsubstantially constant when it is in control of the valve means, meansincluding means responsive to atmospheric conditions outside of theenclosure for intermittently and alternately causing movement of thevalve means to a minimum flow position or placing the valve means underthe control of the flow responsive means in a manner to cause the periodof time during which the valve means is under the control of the flowresponsive means with respect to the period of time the valve means isin the minimum flow position to vary with changes in outside atmosphericconditions to maintain desired temperature conditions within theenclosure.

WILLIAM L. McGRATH.

